Hawaii Oo

The 'Hawaiʻi ʻŌʻō was first described by Blasius Merrem in 1786. It had an overall length of 32 centimetres , wing length of 11–11.5 centimetres , and tail length of up to 19 centimetres . The colour of its plumage was glossy black with a brown shading at the belly. It was further characterized by yellowish tufts at the axillaries. It had some yellowish plumes on its rump, but lacked yellow thigh feathers like the Molokaʻi ʻŌʻō, and also lacked the whitish edgings on its tail feathers like the Oʻahu ʻŌʻō. However it had the largest yellow plumes on its wings out of all the species of ʻŌʻō.

The Hawaii Oo is classified as Extinct (EX), there is no reasonable doubt that the last individual has died.